RNAs That Behave Like Prions
Robert Gorter, MD, PhD. et al.
April 10th, 2021
Messenger RNA Definition
Messenger ribonucleic acids (mRNAs) transfer the information from DNA to the cell machinery that makes proteins. Tightly packed into every cell nucleus, which measures just 10 microns in diameter, is a three-meter long double-stranded DNA “instruction manual” on how to build and maintain a human body. In order for each cell to maintain its structure and perform all of its functions, it must continuously manufacture cell-type-specific parts (proteins). Inside each nucleus, a multi-subunit protein called RNA polymerase II (RNAP II) reads DNA and simultaneously fabricates a “message” or transcript, which is called messenger RNA (mRNA), in a process called transcription. Molecules of mRNA are composed of relatively short, single strands of molecules made up of adenine, cytosine, guanine, and uracil bases held together by a sugar-phosphate backbone. When RNA polymerase finishes reading a section of the DNA, the pre-mRNA copy is processed to form mature mRNA and then transferred out of the cell nucleus. Ribosomes read the mRNA and translate the message into functional proteins in a process called translation. Depending on the newly synthesized protein’s structure and function, it will be further modified by the cell, exported to the extracellular space, or will remain inside the cell. The diagram below shows transcription (DNA-RNA) taking place in the cell nucleus where RNAP is RNA polymerase II enzyme synthesizing RNA.
Functions of mRNA
The primary function of mRNA is to act as an intermediary between the genetic information in DNA and the amino acid sequence of proteins. mRNA contains codons that are complementary to the sequence of nucleotides on the template DNA and direct the formation of amino acids through the action of ribosomes and tRNA. mRNA also contains multiple regulatory regions that can determine the timing and rate of translation. In addition, it ensures that translation proceeds in an orderly fashion because it contains sites for the docking of ribosomes, tRNA as well as various helper proteins.
Proteins produced by the cells play a variety of roles,